PROJECT SUMMARY/ABSTRACT The Molecular Basis of Cell Function (MCF) program addresses the need to provide truly multidisciplinary PhD training in the field of molecular and cell biology at UC Berkeley. Indeed, MCF is the only training program at Berkeley that encourages students to think broadly and explore across the spectrum of sub-disciplines within the field. Accordingly, MCF?s 82 training faculty are recognized scientific leaders, drawn from all five divisions within the Department of Molecular and Cell Biology (MCB): Biochemistry, Biophysics & Structural Biology; Cell & Developmental Biology; Genetics, Genomics, & Development; Immunology & Pathogenesis; and Neurobiology. Their research spans biological scales from molecules to complex systems to whole organisms. This proposal requests support for 40 MCB trainees annually in their first and second years of PhD training. The guiding philosophy of the MCB/MCF program is to provide early and persistent emphasis on student training for a flexible and individually-directed path to innovative research. We provide rigorous cross- disciplinary training, with an emphasis on imparting conceptual knowledge, promoting imaginative and critical thinking, applying new and quantitative approaches, mastering experimental logic and methods, appropriately analyzing and interpreting results, and communicating findings clearly and fluently. To advance multidisciplinary training, we facilitate extensive interactions and collaborations among students and faculty within and across divisions. All students in MCF and MCB programs will receive the same training in Years 1-2 of their PhD, including: a core Fundamentals of Molecular and Cell Biology course; advanced elective coursework in specific subfields; modular courses in quantitative approaches; immersive rotations in three different research areas; rigorous thesis research; student-led seminars; and a new course, Responsible Conduct, Rigor and Reproducibility in Research. A suite of professional development programs provide hands- on training in science communication, teaching, mentoring, teamwork, management, and leadership. Seminar series, symposia, and annual retreats also provide rich exposure to current research. All trainees receive extensive scientific and career advising and mentoring. Improvements to the program are guided by close monitoring of student progress as well as data-driven evaluation of program effectiveness and outcomes. This application builds on, updates, and improves our many years of NIH-sponsored MCF Training Program support. We have a strong track record in recruiting and graduating PhD students from diverse backgrounds. Our students conduct innovative research, publish in top journals, and go on to leadership roles in academia, industry, government, law, education, science communication, and many other fields. Innovative new training elements proposed in this renewal application will further prepare our students to tackle present and future biomedical, scientific, and societal challenges.